The incident occurred at Digghi village under Sadar police station of the district.
Sadar police station SHO Chittaranjan Thakur said that the deceased has been identified as Rajiv Kumar Sharma (40) while his associate, who sustained injuries in the incident, has been identified as Sanjay Kumar.
Both Sharma and Kumar were attacked by lathi and iron rod by a group of 20 people, he said.
Sharma and Kumar used to practise at civil court at Hajipur, SHO said adding that Kumar has been admitted to sadar hospital.
An FIR is being lodged in this connection, he said.
Police have arrested three women in this connection and they are being interrogated at present, he said and added that police are making all efforts to nab the others.